The present invention relates to projection image display apparatuses suitable for projection of images onto a projection surface using a single or plural projectors and multi-projection systems.
Multi-projection systems (image display system) are conventionally used, which project plural images onto a projection surface by combination of plural projectors.
Of the systems, one is known which displays a magnified image by arranging plural image display areas onto which the plural projectors project images in a tiled manner (see Japanese Patent Laid-Open Application No. 2005-39849).
As another image display system, a so-called stack projection system is known in which plural projectors are combined and plural image areas of the respective projectors are overlapped with each other (see Japanese Patent Laid-Open Application No. 2004-228824).
The multi-projection system disclosed in FIG. 1 of Japanese Patent Laid-Open Application No. 2005-39849 divides input image information into plural pieces and displays the pieces of information by the plural projectors that constitute the system. This system displays a smooth image that is a mostly seamless image on a screen.
The stack projection system disclosed in FIG. 1 of Japanese Patent Laid-Open Application No. 2004-228824 overlaps the projection display areas of the respective projectors with high accuracy. This system can obtain a bright projection image by causing the respective projectors to display the same image information.
However, in a case where the respective projectors display images different from each other in the multi-projection system, the stack projection system disclosed in Japanese Patent Laid-Open Application No. 2004-228824 overlaps the different images. This results in making it hard to recognize the projection image.
The multi-projection system disclosed in Japanese Patent Laid-Open Application No. 2005-39849 can display the respective images independently since the respective projection areas are different from each other. However, since the projection areas are fixed, their positions cannot be moved freely.
Further, when a single projector projects an image onto the projection surface, the image and another image projected by another projector may overlap with each other.
Furthermore, when the plural projectors project plural images onto the screen, the projection areas of the images may overlap with each other thereon.